Exhaust muffler with expansion chambers in inlet cover dome



S. J. GIBEL April 30, 1968 EXHAUST MUFFLER WITH EXPANSION CHAMBERS IN INLET COVER DOME Filed April 11, 1966 INVENTOR STEPHEN J. GI BEL ATTORNEYS United States Patent 3,380,553 EXHAUST MUFFLER WITH EXPANSION CHAMBERS IN INLET COVER DOME Stephen J. Gibel, 5846 Edgerton Road, North Royaltou, Ohio 44133 Filed Apr. 11, 1966, Ser. No. 541,702 4 Claims. (Cl. l8l56) This invention relates to mufl ling devices for muffling the noises of a pressure fluid exhaust such as exhaust from a compressed air operated power cylinder, tool or other equipment.

The present invention is an improvement over my earlier Patent No. 2,815,088, granted Dec. 3, 1957, and has as a general object the provision of a novel and improved muflling device for silencing exhaust noise and which is of a relatively simplified but durable construction for more economical manufacture and longer service life.

Another object of this invention is to provide a novel and improved mufiler of the kind wherein dissipation of exhaust fluid noise takes place in a silencing chamber defined in part by a porous wall through which the exhaust fluid is dispersed to the atmosphere and wherein a flat plate-like member having openings is disposed in the path of the exhaust fluid entering the silencing chamber and which diffuses the air and in so doing expends some of the energy of the exhaust fluid and reduces the impact of the fluid on the porous chamber wall.

A still further object of the present invention is the provision of a new and improved muffler for silencing exhaust fluid under pressure discharged from a machine and which muffler includes a tubular, open ended, body; cover members closing the open ends of the body and defining a silencing chamber therein, one of which member includes an exhaust fluid intake passageway and an expansion chamber connected with the exhaust intake; a flat, mesh diffuser member disposed between the expansion chamber and the silencing chamber; and a pair of connectors securing the parts in assembled relationship and offset from the center of the muffler.

The present invention resides in certain constructions, combinations and arrangements of parts and further ob jects and advantages will be apparent to those skilled in the art to which the invention relates from the following description of the preferred embodiment described with reference to the accompanying drawings forming a part of this specification, and in which:

FIG. 1 is a perspective view of a mufiler according to the present invention;

FIG. 2 is a vertical sectional view of the muffler of FIG. 1 taken substantially along line 2--2 of FIG. 3;

FIG. 3 is a plan view of the mufller taken substantially along line 3-3 of FIG. 2;

FIG. 4 is a plan view of the rnufller taken along line 44 of FIG. 2;

FIG. 5 is an exploded perspective view of the muflier shown in FIG. 1; and

FIG. 6 is a diagrammatic view of the mufller illustrating its operation.

As representing the preferred embodiment of the invention, the drawings show an improved muflier 10 comprising a hollow, porous body member or disseminator 12 and a pair of end members or covers 14 and 16 which close the ends of the body member when the parts are assembled. The end members are preferably cast from aluminum.

The top cover member 14 includes a flange portion 18 at the lower end thereof as viewed in the drawings which is adapted to engage one end of the body, an intermediate hollow dome shaped portion 20 and a hollow stem 22 extending axially centrally of the dome. The stem portion is hollow and is provided with exterior threads 24 for connecting the unufller to an exhaust conduit of an associated machine which generates exhaust fluid to be mufiied. The hollow stem portion provides a fluid inlet passageway 26 through which exhaust fluid enters the muifler.

The interior of the hollow dome shaped portion 20 is divided into four expansion and pressure chambers 28, 39, 32 and 34 by a web structure 36. The web structure 36 is formed integral with the interior surface of the dome portion 20 and comprises four vanes or webs 38, 40, 42 and 44 which are interconnected at a junction or deflector 46 disposed in the bottom of passageway 26. The webs extend from the interior surface of the dome portion and their projecting or lower ends are flush with a flat surface 48 forming the horizontal extent of the flange portion '18. The continuous extents of the Webs divide the interior of the dome into the four expansion chambers so that the exhaust fluid entering passageway 26 is divided and directed into the respective chambers and remains separated until discharged therefrom. The exhaust fluid in passageway 26 enters the expansion chambers 28, 30, 32 and 34 through openings 50, 52, 54 and 56 provided in the webs adjacent to the junction and the passageway 26.

The deflector 46 has a flat, even surface portion 46a on the lower exterior side thereof as viewed in the drawings which is flush with the lower ends of the webs. The opposite side 46b of the deflector, i.e., the side exposed to the passageway 26 has a concave configuration as best illustrated in FIG. 2. In the preferred embodiment the deflector closes approximately 60 percent of the passageway 26 which is suflicient to prevent through flow and to deflect the exhaust fluid impinging thereagainst into the chambers. The impingement of the exhaust gases which are in the form of a jet stream with the concave side 46b reverses the flow of the exhaust by deflecting it upwardly against the incoming exhaust fluid thereby creating a back pressure on the incoming exhaust causing the exhaust fluid to expend energy and reduce its velocity. The shape of the expansion chambers permits the fluid to expand upon entry and directs the fluid toward the bottom of the chambers as viewed in the drawings. This expansion also reduces the velocity of the exhaust and causes further expenditure of the energy of the exhaust streams through the chambers.

The bottom of the chambers are partially closed by a fiat diffuser member 58. The diffuser member 58 is in the form of a plate-like member which abuts the lower portion of the web structure 36 and the flush flat surface 48 of flange portion 18 when assembled. The plate-like member or screen 58 is approximately 2% inches in diameter for a mufller having a /2 inch diameter inlet passageway and has a plurality of openings 60 therein through which the exhaust fluid enters a silencing chamber 62. The openings 6% in the screen are A inch holes or openings having their centers spaced about A; of an inch from one another or slightly less and provide approximately a 1:1 relationship of surface area to openings. This relationship has been found to effectively diffuse the streams of exhaust fluid directed thereagainst and creates a controlled fluid cushion acting against exhaust fluid in the chambers to reduce the velocity of the fluid impinging on the screen. Other foraminous material could be used in place of the flat metal screen diffuser in the muffler 10 and the size and spacing of openings 60 could deviate from the disclosed relationship of the preferred embodi ment.

The exhaust fluid flows through openings 60 as jet streams at an angle relative to the plane of the diffuser. The thickness of the diffuser screen is such that the angular flow through the expansion chambers is not altered to a substantial extent when the streams pass through the opening 60 and impinge against the walls of the silencing chamber at an obtuse angle. The silencing chamber is in effect an expansion chamber and is defined by the interior surface 12a of the body 12, the dilfuser member 58 and bottom cover member 16. The body 12 is preferably of cylindrical tubular form and made of a material that is porous or has a plurality of small openin s or passageways through which the exhaust fluid in the silencing chamber is dissipated to the atmosphere. Cellulose fibers available in the form of pliable sheets or strips has been found to be a suitable material for the body member. The body member 12 is formed in the preferred embodiment by winding strips of this cellulose fiber into a tube, impregnated with a phenolic resin such as phenol-formaldehyde and is cured under heat and pressure resulting in a relatively hard and rigid body able to withstand considerable impingement of exhaust fluid without eroding. Constructing the body from material treated in this manner provides a hard body having a rough irregular interior surface 12a which helps to absorb some of the energy of the exhaust fluid upon impact. In the preferred embodiment, the inside diameter of the body is approximately 2% inches and is approximately 4 inches in length, the size varying according to the size of the inlet. Preferably, a ratio in the neighborhood of 6011 is maintained between the exterior surface of the body and the diameter of the inlet passageway. The exhaust fluid impinges against the interior wall surface of the body at an angle and reverberates back and forth between spaced areas of the wall surface 12a and is eventually dispersed through small openings in the porous wall of the body member 12 to the atmosphere.

The body member may be protected against damaging blows to its exterior by a reinforcing member such as a tubular metal member 64 having openings therein disposed about the outer periphery of the body member 12. It should be appreciated that this member not only protects body member 12 from external damage but also prevents a rupture of the body member due to excessive internal pressure and assists the body member in withstanding the clamping pressure exerted thereon by end members 14 and 16.

The parts of the mufiler are secured in their assembled relationship by a pair of connector rods 66, 68 extending from the bottom cover member 16 through the top cover member 14. The bottom cover member 16 has a segmented generally concave interior configuration terminating at a flange 70 which engages the end and outer side of the body member 12. The rods 66, 68extend through a pair of openings 72 in member 16. Bosses 76 formed integral with the interior side of the bottom cover member provide extensions of the openings 72. V

The lower end of each of the connector rods is constructed like a carriage bolt and has a head 80 and a portion 82 adjacent thereto which is substantially rectangular in cross section. The lower ends of the openings 72 are also rectangular in cross-sectional configuration and the portions 82 of the rods 66, 68 fit therein to prevent the connector rods from turning in the openings. The rods extend through the bottom cover member 16, through the silencing chamber 52, through openings provided in the diffuser screen and through openings provided in the bosses 84 formed integral with the top cover member 14. The upper projecting ends of the connector rods are threaded and have suitable lock nuts 86, 88 thereon. The connector rods and nuts secure the parts of the mufiler in rigid assembly and prevent loosening of the parts and subsequent disassembly due to vibration. Utilizing a plurality of connector rods offset from the center of the muffler as distinguished from a single centrally located rod provides the additional advantage that it avoids the use of a rod co-axial with the inlet passageway and thus reduces the complexity of top cover member 14 in providing connections for the rods.

The mode of operation of the muffler described can best be understood by reference to FIG. 6 which is 21 diagrammatical representation of the muflicr and depicts '4 by means of arrows the flow of exhaust pressure fluid through the muffler.

The mufiler 10' operates to reduce the noise level of the fluid pressure exhaust by reducing the velocity of the exhaust fluid and causing the fluid to expend energy as it flows through the muffler so that the exhaust is subsequently dispersed to the atmosphere silently. This is accomplished by dividing main stream of exhaust into four streams, expanding the four streams, dividing the four streams into numerous smaller streams and directing the streams against one another which reduces the dynamic energy of the fluid pressure exhaust. The theory of operation of the muffler is believed to be as follows. Exhaust fluid enters the mufi'ler through the inlet passageway 26 in the form of a stream of air under high pressure and this stream is represented by three arrows in FIG. 6. The incoming stream moves through the passageway and the central portion thereof impinges against the concaved surface 46b of the deflector 46 in the bottom of the passageway 26. The concave configuration of the deflector causes the exhaust stream to reverse its direction of movement and moves toward the sides of passageway 26 in opposition to the oncoming stream of exhaust fluid reducing the energy thereof. As stated previously, the deflector 46 does not close the entire area of the passageway 26 but due to the concave configuration thereof, the deflected streams of air oppose the incoming exhaust stream reducing its velocity and prevents the portions of the incoming jet stream around the central jet from flowing about the deflector onto the diffuser member 58. The impingement of the central jet with the deflector 46 also reduces the velocity of the streams and energy therein.

The deflected exhaust fluid enters the expansion chambers 28, 30, 32, 34 in the dome shaped portion 20 of the cover member 14 through openings 58, 52, 54 and 56. The main exhaust stream is thus divided into four streams which are permitted to expand in the expansion chambers and are directed through the expansion chambers and into impingement against the upper surface of the diffuser plate 58 disposed along the bottom of the expansion chambers. Some of the exhaust in the chamber passes directly through the openings 60 in the diffuser members while other parts thereof impinge against the solid portion of the diffuser member and creates a cushion of pressure opposing the oncoming fluid in the expansion chamber. This opposition reduces the velocity of the oncoming fluid in the chambers causing the exhaust fluid therein to expend energy. The expansion of the fluid in the chamber and the frictional engagement with the chamber surfaces, likewise, causes the exhaust to expend energy.

The fluid moves through the openings 60 as jets of air under presure at an angle to the plane of the diffuser screen and create alternate areas of pressure and vacuum along the underside of the diffuser member. Specifically, the vacuum areas are established at the closed areas and the pressure areas are at the openings. The jets of fluid flowing through the openings diffuse upon entering the silencing chamber 62 and bend or veer from their downwardly course as illustrated in the drawings, causing the jets to mix and produce a zone of turbulence. This zone of turbulent air is subsequently forced downwardly in the chamber 62 impinging against the interior surface 12a of the wall of the body member producing a crisss-cross flow pattern as the exhaust reverberates in the silencing chamber. The expansion and continual impact with the interior wall surface 12a and with other parts of the exhaust fluid pressure streams in the silencing chamber further reduces the energy and velocity of the exhaust. The turbulence zone of air prevents the jets of air from impinging directly upon the bottom cover member and opposes the jets enterll'lg the silencing chamber. The streams move downwardly in the silencing chamber in a criss-cross pattern and the concave interior configuration of the bottom end cover member forms a receptacle for receiving and retaining pressure. This pressure acts as a fluid cushion to further expend velocity and energy of the exhaust in the silencing chamber. The exhaust fluid is subsequently dissipated into the atmosphere through the small openings in the wall. The openings in the wall are very small and absorb or expend any noise energy remaining in the exhaust and cause further reduction of the velocity so that the exhaust discharged from the muffler is silent.

From the foregoing description, it should be apparent that the invention provides a novel and improved mufiier for silencing the noise and reducing the velocity of a pressure stream of fluid exhaust so that the exhaust is discharged in gentle waves of low velocity tone.

Although the preferred embodiment of the present invention has been described in considerable detail, it should be apparent that changes and modifications could be made therein without departing from the scope of the invention as defined in the claims. For example, other types of foraminous material could be used as a diffuser, the size and spacing of openings 60 of difiuser member 58 could be varied from the arrangement described and the body 12 could be constructed from materials other than thecellulose fiber material disclosed. It should be further appreciated that the improved muffler requires a minimum number of parts which may be economically manufactured and readily assembled so as to provide an economical article of manufacture with a substantially long life.

Having described my invention, I claim:

1. In a mufller adapted to silence the exhaust fluid pressure of a machine, a tubular open ended body, a pair of cover members adapted to engage and close the ends of said body to form a silencing chamber, one of said cover members having a fluid inlet passageway through which exhaust fluid is adapted to enter the muffier, said one cover member further having an expansion chamber in communication with said inlet passageway, a diffuser member having a plurality of openings therein arranged intermediate said expansion chamber and said silencing chamber, said body having a plurality of apertures therein opening said silencing chamber to the atmosphere, and means for securing said body, diffuser member and cover members in assembled relationship.

2. In a muffler adapted to silence the exhaust fluid pressure of a machine, an open ended hollow body, a pair of cover members adapted to engage and close the ends of said body to form a substantially closed silencing chamber, one of said cover members having a fluid inlet passageway through which exhaust fluid is adapted to enter the muffler, said one cover member further having a plurality of expansion chambers in communication with said inlet passageway, a diffuser member having a plurality of openings therein and arranged intermediate said one cover member and said body, said body having a plurality of apertures therein opening said silencing chamber to the atmosphere, a plurality of connector rods extending between said cover members, each of said rods having a threaded end, and threaded fasteners connected to the threaded ends of said rods to secure said cover members in clamping engagement with the ends of said body.

3. In a muffler adapted to silence the exhaust fluid pressure of a machine, an open ended hollow body, first and second cover members adapted to engage the ends of said body to form a substantially closed silencing chamber, said first cover member having a hollow stem extending axially therefrom which is adapted to be connected to an exhaust conduit of a machine, said stern defining a fluid inlet passageway adapted to direct exhaust fluid into the mufller, said first cover member further having a web structure on the underside thereof which divides the underside into a plurality of expansion chambers, a plurality of openings in said web structure communicating said expansion chambers with said inlet passageway, a flat diffuser plate having a plurality of holes therein and arranged intermediate said first cover member and said body, said body having a plurality of small passageways opening said silencing chamber to the atmosphere, and means for connecting said cover members, said plate and said body in assembled relationship.

4.5In a mufiler adapted to silence the exhaust fluid pressure of a machine, an open ended, hollow porous body, first and second cover members adapted to engage the ends of said body to form a substantially closed chamber, said first cover member having a hollow stem extending axially therefrom which is adapted to be connected to an exhaust conduit of a machine, said stem defining a fluid inlet passageway for directing fluid into the mufller, said first cover member further having a web structure formed integral with the underside thereof and which forms a plurality of expansion chambers, said web structure having a deflector disposed in said inlet passageway to deflect the incoming exhaust into said expansion chamber through a plurality of openings in said web structure, a flat diffuser plate having a plurality of holes therein and arranged intermediate said first cover member and said body, the porous nature of said body providing a plurality of small passageways through which the exhaust fluid is dispersed from said chamber into the atmosphere, said second cover member having a pair of hollow sleeves providing rod receiving openings therethrough, a pair of rod receiving openings in said diffuser screen and in said first cover member which are alignable with the rod receiving openings in said second cover member, a pair of connecting rods having an enlarged head on one end and threads on the opposite end thereof and adapted to extend through said aligned rod receiving openings with the threaded ends projecting from said first cover member, threaded fasteners secured on the thread ends of said connector rods to secure said end cover members in clamping engagement with the ends of said body.

References Cited UNITED STATES PATENTS 1,479,714 1/1924 Herdle 18l55 1,626,908 5/1927 Armstrong 181-49 2,600,236 6/1952 Gibel 18156 2,815,088 12/1957 Gibel 18l--56 FOREIGN PATENTS 278,547 10/1930 Italy. 308,088 9/ 1955 Switzerland.

ROBERT S. WARD, J 11., Primary Examiner. 

1. IN A MUFFLER ADAPTED TO SILENCE THE EXHAUST FLUID PRESSURE OF A MACHINE, A TUBULAR OPEN ENDED BODY, A PAIR OF COVER MEMBERS ADAPTED TO ENGAGE AND CLOSE THE ENDS OF SAID BODY TO FORM A SILENCING CHAMBER, ONE OF SAID COVER MEMBERS HAVING A FLUID INLET PASSAGEWAY THROUGH WHICH EXHAUST FLUID IS ADAPTED TO ENTER THE MUFFLER, SAID ONE COVER MEMBER FURTHER HAVING AN EXPANSION CHAMBER IN COMMUNICATION WITH SAID INLET PASSAGEWAY, A DIFFUSER MEMBER HAVING A PLURALITY OF OPENINGS THEREIN 